Argentina may have dodged La Nina bullet

It appears that La Nina won’t be taking too big of a toll on Argentina’s corn and soybean crops, and the reason may seem counter-intuitive, says a weather expert.

La Nina weather events are often associated with drought in Argentina and southern Brazil.

However, researchers have discovered a surprising correlation between the intensity of the La Nina event and the extent of crop damage.

Weaker La Nina events have consistently caused more soybean and corn yield damage than stronger La Nina events over the past couple of decades, said Mark Brushberg, chief meteorologist with the U.S. Department of Agriculture’s Office of the Chief Economist.

He told delegates attending the USDA’s 97th annual Agricultural Outlook Forum that lots of people in the crop sector make South American production assumptions based on the mere presence of La Nina.

That is a dangerous approach because every La Nina is year is different.

“You have to watch out,” said Brushberg.

“Don’t assume that Argentina is going to have a drought because it’s a La Nina.”

This is one of those strong La Nina years and it doesn’t appear that corn and soybean yields will be severely reduced.

“They had some challenges but they did get the rain, and temperatures were not that bad,” he said.

Cumulative precipitation levels as of early February are well below the 30-year average, but they seemed to be more closely tracking the levels of the 2010-11 La Nina year rather than the disastrous 2017-18 event.

In 2010-11, corn yields were five percent below average and soybean yields were two percent lower than the trend line.

That compares favourably to 2017-18, when corn yields were 22 percent below normal and soybean yields were 20 percent lower than average.

Drew Lerner, president of World Weather Inc., thinks the correlation between Argentina’s yields and the intensity of the La Nina event is more coincidence than science.

He acknowledged that yields have been more severely impacted by weaker La Nina events than stronger events over the past couple of decades.

However, he thinks that has more to do with other weather patterns than it does with the intensity of the La Nina.

“I think the big mistake that people make is that when La Nina or El Nino is around they immediately assume that will control the weather completely,” he said.

That is not the case.

For instance, this year the 18-year cycle is having a big impact on Argentina’s weather, providing timely precipitation for the country’s crops.

Lerner said drought hurt early-season crops like sunflowers and the first crop of corn, but late-season crops like soybeans have benefitted from more routine rainfall due to the 18-year cycle.

He is forecasting hot and dry conditions in Argentina through the first week of March, which will deplete topsoil moisture and diminish subsoil moisture.

Lerner said half of the crop is still in the reproduction and filling stages of development and needs additional moisture in March to maintain yields.

“It’s still tenuous. Yields could still go down,” he said.

A general soaking rain is needed in the second week of March to curb drought stress. World Weather sees some relief that week but not a soaking rain.

Contact sean.pratt@producer.com

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